Technical Field
The invention relates to a granular material spreader, and in particular to a drop spreader apparatus. More particularly, the invention is directed to a sidewalk drop spreader for winter services, which can be mounted on most all-terrain vehicles (ATVs), utility-terrain vehicles (UTVs), and compact tractors. The sidewalk drop spreader is capable of spreading an array of deicing materials with precision flow control, includes a narrow frame design that makes it ideal for spreading material on sidewalks and other narrow walkways, and includes an innovative agitation system that prevents material bridging and eliminates the need for a traditional, noisy vibration motor.
Background Art
There are two principal types of granular material spreaders in the art, broadcast spreaders and drop spreaders. These spreaders commonly spread materials such as seed, fertilizer, salt, sand, or other dry material.
Broadcast spreaders are comprised of a rotating member that centrifugally disperses the granular material from the spreader. The amount and concentration of the granular material being dispersed is controlled by adjusting the flow or amount of material being delivered to the rotating member and/or adjusting the speed of the rotating member.
However, broadcast spreaders may have issues with reliability. Material flow rate is often regulated with a “gate” that is controlled by a cable. Cables are susceptible to corrosion, resulting in machines that must be continuously maintained to ensure that the cables are in working order. In addition, broadcast spreaders struggle to provide precision control over the material spread rate, which undesirably results in wasted material and wasted cost.
Due to their nature of centrifugally dispersing and thus throwing material outwardly from a central point, broadcast spreaders also have issues with maintaining a consistent spread rate and a uniform spread width or pattern. Because broadcast spreaders do not control the spread width or pattern accurately enough, uncontrolled or uneven spread of material occurs. When the broadcast spreader is used for winter services, such as to spread deicing materials that include salt, sand, calcium chloride, magnesium chloride, and the like, such uncontrolled or uneven material spread causes damage to surrounding turf and/or landscaping, as well as causing inconsistent deicing.
As a result of these shortcomings associated with broadcast spreaders, drop spreaders were developed and are well known in the art. A drop spreader is similar in purpose to a broadcast spreader, but there are fundamental differences. In general, a drop spreader is a machine that distributes a calibrated amount of material from a hopper to the ground over approximately the width of the spreader. A rotor, which is a cylinder that rotates about a horizontal axis, is typically located in the bottom of the hopper to meter material out of an opening in the bottom of the hopper. The rate at which material is spread by a drop spreader, which is referred to as the drop rate of the spreader, is typically determined by the rotational speed of the rotor, the size of the bottom opening in the hopper, or both.
Due to the differences in construction and operation between a drop spreader and a broadcast spreader, a drop spreader typically includes a more precise rate of application of material, and a more controlled width of application of material, than a broadcast spreader.
A majority of the drop spreaders in the prior art are push or tow behind units that were designed for seeding or fertilizing applications. Because drop spreaders were originally designed for spreading fertilizers and seed, which are dry materials that flow relatively easily with gravity, only light agitation or vibration of the hopper was required. When drop spreaders were employed to spread salt or other deicing materials, which do not flow as easily, the use of gravity alone or light agitation frequently results in the stoppage of flow or “bridging” of material, to the point that the resulting spread rate is inconsistent or non-existent. For this reason, salt and other deicers may require substantially more agitation or vibration to assist in material flow.
As a result of this need for more agitation and vibration when dealing with salt and other deicing materials, drop spreaders in the prior art for winter services have been designed with specific features. More particularly, such drop spreaders typically employ a secondary agitator or a vibrator to assist in material flow for the spreading of salt and/or other deicing materials. The secondary agitator is used in addition to the primary rotor, and is a secondary rotational device that is placed above the rotor in the hopper. As the secondary agitator rotates, it essentially stirs the material, preventing it from bridging so that the material is consistently present at the rotor to provide a uniform flow. The vibrator is a vibratory device that is also used in addition to the primary rotor, and is mounted to the hopper. The vibrator operates at a high frequency to shake the hopper to facilitate uniform material flow, and can be hydraulically or electrically powered. The use of a secondary agitator or a vibrator undesirably increases the power demand of the drop spreader, undesirably adds components and cost to the drop spreader, undesirably increases the wear on the hopper, rotor, and other components, and in some cases, undesirably creates excessive noise.
For application of salt and/or other deicing material to confined areas such as sidewalks on a large scale, including school campuses and commercial institutions, drop spreaders are often mounted on small vehicles, such as ATVs, UTVs, and compact tractors. The drop spreaders typically are connected to the power source of the vehicle and are powered either by a power takeoff (PTO), hydraulics or electrically. A PTO involves transmitting engine power from the vehicle to the drop spreader using a drive shaft or a drive belt, hydraulic power involves a hydraulic hose connection between the vehicle and the drop spreader, and electric power involves a wire connection with a pin or plug connector. Prior art drop spreaders that employ a PTO or a hydraulic connection experience disadvantages having to do with their method of power, method of control for material drop rate, and method of connecting to the vehicle.
More particularly, in regard to their method of power, drop spreaders that are powered by a PTO or hydraulically are not compatible with many compact vehicles, as PTO or hydraulics typically require an agricultural-type tractor or a skid-steer vehicle. As for the method of control for material drop rate, drop spreaders that are powered by a PTO or hydraulically have a rotor speed that is directly proportional to engine speed. To change the drop rate, the size of the hopper opening must be adjusted. Such adjustments cannot be done from the operator seat unless a cable is used, which undesirably increases the cost and complexity of the spreader. In regard to the method of connecting to a vehicle, the PTO powered drop spreaders undesirably have the increased cost and complexity of a drive shaft, drive belt, or some other mechanical power transfer, with a corresponding PTO and clutch on the vehicle. Hydraulically powered spreaders include hydraulic hoses that connect to the vehicle with a hydraulic system and control valve on the vehicle, which are undesirably expensive to purchase and maintain.
Electrically-powered drop spreaders are typically easier to connect to the vehicle, to power, and to control, and are thus seen as being advantageous over PTO and hydraulically powered drop spreaders. However, prior art electrically powered drop spreaders include certain disadvantages.
For example, prior art drop spreaders that are powered electrically require a large amount of amperage to operate them. More particularly, the requirement of a secondary agitator or a vibrator, as described above, undesirably increases the power demand of the drop spreader. Because a small vehicle such as a tractor, lawnmower, or four-wheeler has a limited charge capability in a range between about 15 to 50 total amps, there may not sufficient power or charge capacity to power the spreader, the vehicle electrics, and lights.
In addition, prior art electric powered spreaders have a power cable that connects to the vehicle wiring system or battery. A power switch and/or variable speed controller must be present to control the spreader, and is typically located on the vehicle and connected to the spreader with a wire harness that must be installed on the vehicle. Such a connection undesirably increases the initial cost of the drop spreader, and also undesirably increases the cost to maintain the spreader, as the wires are susceptible to corrosion.
The disadvantages of the prior art make it desirable to develop an economical and reliable drop spreader that is electrically powered, removably mounted on a compact tractor, ATV, or UTV to enable a more convenient, more efficient method of spreading salt or other deicing material than a tow behind or push spreader, and provides a precise rate of material spreading, controlled width of material spread, uniform spread pattern, material savings, and labor savings. The sidewalk drop spreader for winter services of the present invention satisfies these needs, as will be described in detail below.